#include <iostream>
#include <thread>

using namespace std;

class Thread {
   public:
      Thread(int i) : id(i) {};
      Thread(const Thread& other) : id(other.id) {};
      void operator()() {
	 cout << "thread " << id << " is operating" << endl;
      }

   private:
      const int id;
};

int main() {
   // fork off some threads
   thread t1(Thread(1));
   thread t2(Thread(2));
   thread t3(Thread(3));
   thread t4(Thread(4));
   // and join them
   cout << "Joining..." << endl;
   t1.join(); t2.join(); t3.join(); t4.join();
   cout << "Done!" << endl;
}